The present invention relates to a method of forming a ferroelectric film using a metalorganic chemical vapor deposition method.
In recent years, as a technology of forming a ferroelectric film which is expected to be applied to a ferroelectric memory and a piezoelectric device, a deposition technology using a metalorganic chemical vapor deposition (MOCVD) method used in the crystal growth technology of compound semiconductors has attracted attention in order to improve mass production capability.
However, in the case of depositing a complex oxide of lead zirconate titanete (PZT) family on a Pt metal film used as an electrode material, since the crystal lattice matching between the complex oxide of PZT family and the Pt metal film is poor, it is difficult to obtain a ferroelectric film having an excellent crystallization state by using a conventional deposition technology using the MOCVD method. In the case of depositing a complex oxide of PZT family by using the MOCVD method, the complex oxide of PZT family is generally deposited by supplying material gases for all the constituent elements at the same time. In the case of depositing a complex oxide of PZT family on a Pt metal film, a technology of forming a TiOx film between the Pt metal film and the PZT complex oxide crystal as a buffer layer by supplying only a Ti material and an oxidizing gas has been proposed in order to reduce the above-described lattice mismatch. However, since the orientation of the crystal of the TiOx film may adversely affect the orientation of the PZT complex oxide crystal, a technology which can replace this technology has been demanded.